Apparatus and method for continuous production of electrolytically treated wires

ABSTRACT

Apparatus and method for continuously producing electrolytically treated wires which comprise immersing a wire repeatedly in an electrolyte contained in an electrolytical treatment tank positioned between guide rolls which passing the wire continuously back and forth between the guide rolls by guiding the wire stepwise on the guide rolls, using the wire as an electrode and providing another electrode within the electrolytic treatment tank to effect electrolytic plating and/or polishing at a high production efficiency.

United States Patent Kamata et al. [4 1 July 11, 1972 [541 APPARATUS ANDMETHOD FOR 2,495,695 1/1950 Carmin et a1. ..204/209 CONTINUOUSPRODUCTION OF 3,259,557 7/1966 Smith et a1 .204/28 ELECTROLYTIC ALLYTREA D 3,436,330 4/1969 Wright et al., ..204/207 WIRES TE 830,093 9/1906 Meaker ..204/206 2,876,191 3/1959 Bachman... ....204/207 [72] 1mm:g 'f'ggy figzl Takashi FOREIGN PATENTS OR APPLICATIONS ssig The F ukawaCompany Lilnited, 1 Great T k 0 Japan Primary ExaminerF. C. EdmundsonFiledi J 1970 Altomey-McGlew and Toren [21] Appl. No.: 891 ABSTRACT [52]U S Cl 204/206 204/28 204/40 Apparatus and method for continuouslyproducing electrolyti- I o t i i v n t t 9 5i a re- [51] Int Cl C23bC23b 5/58 C23!) 5/6'8 peatedly in an electrolyte contained in anelectrolytical treat- [58] Fieid 6 ment tank positioned between guiderolls which passing the wire continuously back and forth between theguide mus y guiding the wire stepwise on the guide rolls, using the wireas [56] References Cited 1 an electrode and providing another electrodewithin the elec- UNITED STATES PATENTS trolytic treatment tank to effectelectrolytic plating and/or polishing at a high production efficiency.2,293,810 8/1942 Domm ..204/28 2,497,894 2/1950 Luke ..204/28 5 Claim, 4Drawing Figures APPARATUS AND METHOD FOR CONTINUOUS PRODUCTION OFELECTROLYTICALLY TREATED WIRES therefore a very long electrolytic cellhas been required in case a long time treatment is necessary. And incase a plurality of wires are treated at a time, the electrolytic cellmust have also a considerably large width.

Further, such a conventional apparatus has a defect that the cost ofelectrolytic treatment is high due to the necessity of a large amount ofelectrolytic, the difficulty in maintenance of electrolytic and poorworking efficiency.

Therefore, one of the objects of the present invention is to overcomethe above defects and to provide an apparatus which permits a continuouselectrolytic treatment of metal wires at high efficiency. The mainfeature of the present invention lies in an apparatus and method forproducing electrolytically treated wires, which comprises a means forguiding metal wires to be treated, at least one pair of guide rollsserving also as electrode contacts and an electrolytic treatment tankcontaining an electrolyte in which the metal wires are immersed, saidguide rolls being positioned outside the electrolyte, said electrolytictreatment tank being provided with one electrode, and said metal wiresserving as another electrode connected to said guide rolls.

The apparatus and method for producing electrolytically treated wiresaccording to the present invention may be also useful for bothelectrolytic polishing and electro-plating of metal wires, andparticularly in case of electro-plating of metal wires where the wiresare repeatedly passed in and out of the plating bath to give a multiplelayers of plating the present invention is advantageous in that multiplelayers of electro-plating of desired thickness having betteradhesiveness, because when the wires are taken out of the plating tankduring the repeated passing in and out of the plating tank, the surfaceof the plated wires can be maintained in wetted condition by liquidshower or liquid spray.

In one embodiment of the present invention, the electrolytic treatmenttank is provided with slits at the inlet and the outlet thereof forpassing the wires and preventing the electrolyte, and a forcedcirculation system for the electrolyte is used for forcedly returningthe electrolyte which flows out of the inlet and outlet to theelectrolytic treatment tank so that a constant amount of electrolyte ismaintained in the electrolytic treatment tank.

Regarding the guide rolls, their rotating shafts may be horizontal orperpendicular, and the means for guiding the wires provided on the guiderolls may be conveniently a plurality of grooves provided around thecircumferential surfaces of the guide rolls.

The wires to be treated according to the present invention arepretreated in a pre-treatment tank as required.

For better understanding of the present invention, one embodiment of thepresent invention will be described referring to the attached drawingsin which:

FIG. 1 to FIG. 4 show respectively one embodiment of the apparatus forproducing electrolytically treated wires according to the presentinvention;

FIG. 1 is a plane view,

FIG. 2 is a side view,

FIG. 3 is a slant view of the guide rolls and FIG. 4 is a slant view ofthe electrolytic.

In FIGS. 1 and 2, 1 is an electrolytic treatment tank, 2 is anelectrical conductive guide roll, 3 is a shaft of the guide roll 2, 4 isa groove on the circumferential surface of the guide roll 2, 5 is a wireto be treated, which is used as cathode in case of an ordinaryelectro-plating, and is used as anode in case of electrolytic polishing,6 is an electrode plate arranged within the electrolytic treatment tank1, which plate is used as an anode in case of electro-plating and usedas cathode in case of electrolytic polishing, 7 is a contact which iscontacted with and rotated by the guide roll 2, 8 is a distributionline, 9 is an electric power source for the electrolysis, 10 is afeeding drum, 11 and 12 are respectively pretreatment equipment, 13 and14 are respectively after-treatment equipment, and 15 is a coiling drum.In FIG. 3 which is a slant view showing the guide roll 2 in operation, aplurality of guiding grooves are made on the circumferential surface ofeach of the two guide rolls 2a and 2b, so that the wire 5 to be treatedis wound and received in these grooves as shown in the drawing and isdelivered in the direction shown by an arrow as the guide rolls 2a and2b rotate. FIG. 4 is a slant view of the electrolytic treatment tank 1in which the wire to be treated travels in the direction shown by anarrow.

- In the embodiment of the present invention shown in the drawings, twoelectrolytic tanks la and lb extending in the travelling direction ofthe wire 5 are arranged in parallel to each other, at both ends of thesetwo treatment tanks are arranged the guide rolls 2a and 2b eachvertically and rotatably. These'rolls 2a and 2b are connected to theelectrodes of the electric power source 9 through contacts, and theelectrolytic treatment tanks la and lb are also connected to the powersource 9 through the electrode plate 6. 16 is a dividing platepositioned in the tank inward the wire inlet and the wire outlet, and 17is a side wall of the treatment tanks la and lb.

In the above embodiment each of the dividing plate 16 and the side wall17 is provided with narrow slits I8 and 19 respectively for passing thewire therethrough. Thus, the wire 5 passes through the slits 18 and 19and advances without contacting the dividing plate 16 and the side wall17 of the tank. The electrolyte contained in the central portion definedby the dividing plates 16 in the tank 1 drops through the slit I8 into aspace 20, but returned into the central portion of the treating tank bya circulating system (not shown in the drawings) for repeated use. Bysuitable selection of the slit size and the circulating system, the lossof electrolyte is advantageously avoided.

The wire 5 delivered out from the delivery drum 10 passes through thepre-treatment tanks 11 and 12 and is guided into the lowest groove 4a onthe guide roll 2a, then passes through the electrolytic treatment tankIn into the lowest groove 4b on the guide roll 2b, and passes throughthe electrolytic treatment tank 1b into the groove 4c next to the loweston the guide roll 2a.

The wire 5 passes from the guide roll 2a through the electrolytictreatment tank la, the guide roll 2b, the electrolytic treatment 2b intothe top groove 48 on the guide roll 2b and then passes through theafter-treatment tanks 13 and 14 and is coiled on the winding drum.

In the above embodiment of the present invention, the treatment tanks,the slits and the guide rolls are described as being in a tandemarrangement. But the same principle can be applied when the treatmenttanks, the slits and the guide roll are arranged in parallel. In thisway, the wire 5 is subjected to electrolytic treatment during itspassage through the electrolytic tanks 1a and 1b.

According to the present invention, a very high efficient and excellentelectrolytic treatment can be attained as clearly understood from thefollowing examples.

EXAMPLE 1 A brass (Cu 65%, Zn 35%) wire of 2 mm diameter coiled on adelivery drum 10 was taken out from the drum and immersed in NaOHaqueous solution for several seconds, washed with water and themsubjected to nickel plating in the plating apparatus according to thepresent invention as under,

The composition of the nickel plating bath:

Nickel sulfate 250 g/l Boric acid 30 gll Nickel chloride g/l The guiderolls were made of 25 cm diameter stainless steel rolls and rotated at aconstant speed of 15 rpm to obtain the wire speed of 11.8 m/min. Thelength of the nickel plating bath in each of the two tanks was in andthe wire was wound in 30 stepwise so that the length of the totalimmersed wire was 300 meters (30 steps X 2 tanks X 5m). The inputcurrent density was 5 A/dm at 100 percent current efficiency so that thethickness of nickel coated on the brass wire was 25 micron,

In order to attain the same level of production rate as above by aconventional plating method used for the production of nickel platedbrass wire. Such an extraordinary length of plating tank as 300 m atleast is required, and on the other hand the production rate will beabout 1/60 if the production is made at a similar floor area as shown inthis example.

EXAMPLE 2 A steel wire of 20 mm diameter coiled on a delivery drum wasimmersed for several seconds in an aqueous solution of orthosodiumsilicate, washed with water, and then subjected to copperelectro-plating for 1 minute in an electrolyte containing 20 g/l ofcopper cyanide, 43 gll of potassium cyanide, and again washed withwater, subjected to stick tin-plating, washed with water, dried andcoiled on the drum 15. The above thick tin-plating was done as under.

The plating bath contained 120 g/l of potassium stannate only. The guiderolls 2 were titanium rolls of 25 cm diameter and rotated at a constantspeed of 15.0 rpm so that the speed of the copper plated steel wire was11.8 m/min. The bath length in each of the two treating tanks was 5 mand the wire was wound in 30 stepwise so that the total length ofimmersed wire was 300 meter (30 steps X 2 tanks X 5 m). The imputcurrent density was 283 A/dm at current efficiency of 85 percent so thatthe thickness of tin coated on the copper plated wire was 10.5 micron.

In order to attain the same level of production rate as above by aconventional plating method used for the tin-plated steel wire, such anextraordinary length of plating tank as 300 meters at least is required,and a considerable additional width of tank will be required even incase of a multiple electroplating is effected. On the other hand, theproduction rate will be about 1/50 if the production (plating) is madeat a similar floor area as shown in this example.

EXAMPLE 3 In this example, the same electro-plating apparatus and thesame wire speed as in Example 2 were used for cadmium plat ing. A brasswire of 1.5 mm diameter was pre-treated in a similar way as in Example 1and plated with copper and subjected to a thick cadmium plating in abath containing 30 g/l of cadmium oxide and 120 g/l of sodium cyanide ata current density of 565 A/dm to obtain 35 micron thickness of uniformcadmium plating on the wire under the same plating conditions as inExample 1.

The tin-plated steel wire obtained in Example 2 and the cadmium-platedbrass wire obtained in Example 3 were found to be free from surfacecrachings and to have uniformity and high adhesion.

From the above description, it will be understood that a large equipmentrequiring a very large floor area as needed in the conventional arts isnot necessary in the present invention, and much easier quality controland better working efficiency and thus much economical advantages aswell as the technical advantages that better quality of plated wire canbe obtained in the present invention.

EXAMPLE 4 Pure copper wire of 3.0 mm diameter coiled on the delivarydrum 10 was degreased for 30 seconds in trichlor ethylen vapor, thensubjected to polishing in an electrolytic polishing apparatus accordingto the present invention, and washed with water, dried and coiled. Theelectrolytic polishing was done as under. The electrolyte was aphosphoric acid (specific gravity 1.5 g/cm") streight composition. Theelectrolyte was effected at 25 C., at current voltage of 1.6V. The guideroll 2 in the inventive electrolytic polishing apparatus was made oftitanium having 25 cm diameter, and rotated at a constant speed of 5.1rpm so that the wire speed was 4 m/min. Two electrolytic treatment tankswere used. The length of treating bath in each of the tanks was 1 m, andthe wire was wound in 30 stepwise so that the total length of wireimmersed in the electrolyte was 60 m (30 steps X 2 tanks 1m).

The immersion time (polishing time) is calculated from the above factorsas 60 m 4 m/min. 15 min.

As clear from the above, the inventive apparatus is one having such anextraordinarily high working efficiency as permits a high-speedelectrolytic polishing of 4 m/min. in a tank havingonly one meter lengthfor as long as 15 minutes. In this example, the copper wire having alarge diameter and high electrical conductivity was used. if wires suchas steel wires of less electrical conductivity and smaller diameter aretreated, further advantages can be obtained, for in case of a long timeelectrolytical polishing of steel wires in a conventional apparatus, itis necessary to provide current contacts at many various points, if thecurrent is input to the wire used as the electrode, thus a very highlevel of equipment cost is required.

As described above, the present invention can eliminate the efect of aconventional apparatus that a very large apparatus occupying a largefloor area is required, and can provide remarkable advantages that thequality control in electrolytic treatments is much easier, that betterworking efficiency and thus a very high economy can be obtained as well,that a good quality of electrolytically treated wire can be obtained,that particularly the anode (in case of electroplating) can be easilyand continuously supplemented, and that intermediate electrode contactsneeded by an ordinary apparatus for a long period treatment can besubstituted by the grooved rollv The apparatus of the present inventionis useful for a very wide range of applications and can be used for allkinds of electrolytic treatments and can produce all kinds ofelectrolytically treated wires only by selection of the electrolyte, thegroove number on the contact roll, the wire speed and the connection topower source.

What is claimed is:

1. Apparatus for electrolytic treatment of wire comprising tank meanscontaining electrolyte therein, a pair of rollers positioned on oppositesides of said tank means, said rollers being formed of electricallyconductive material, counter electrode means located within said tankmeans, said wire to be treated being spirally wound in a continuousmanner about said rollers and extending back and forth therebetween andthrough said tank means, means forming an electrical circuit pathexternally of said tank means between each of said rollers and saidcounter electrode means thereby to form within said tank means anelectrolytic cell including said wire as an electrode thereof, saidrollers being located completely externally of said tank means, and wallmeans located interiorly of said tank means and defining slots throughwhich said wire extends for retaining said electrolyte within said tankmeans while enabling said wire to pass into and out of said tank means,said tank means being totally devoid of rollers on the interior thereof.

2. Apparatus according to claim 1, wherein said rollers each comprise anaxis of rotation arranged parallel to each other and wherein said slotsextend in a direction parallel to said axes.

3. Apparatus according to claim 1, wherein said counter electrode meanscomprise a pair of electrodes juxtaposed on opposite sides of said wirepassing within said tank means, said pair of electrodes each extendingfor equivalent distances across the length of said wire.

4. Apparatus according to claim 1, wherein said tank means comprise apair of separate tanks adjacently arranged to have said wire whichextends between said rollers pass through one of said tanks in onedirection and through the other of said tanks in an opposite direction.

5. Apparatus according to claim 1, wherein said pair of rollers eachcomprise circumferentially formed grooves on the surface thereof forguiding said wire thereabout.

2. Apparatus according to claim 1, wherein said rollers each comprise anaxis of rotation arranged parallel to each other and wherein said slotsextend in a direction parallel to said axes.
 3. Apparatus according toclaim 1, wherein said counter electrode means comprise a pair ofelectrodes juxtaposed on opposite sides of said wire passing within saidtank means, said pair of electrodes each extending for equivalentdistances across the length of said wire.
 4. Apparatus according toclaim 1, wherein said tank means comprise a pair of separate tanksadjacently arranged to have said wire which extends between said rollerspass through one of said tanks in one direction and through the other ofsaid tanks in an opposite direction.
 5. Apparatus according to claim 1,wherein said pair of rollers each comprise circumferentially formedgrooves on the surface thereof for guiding said wire thereabout.